C172 and Cherokke have completely different stacks, not a single gauge is identical. Some may be similar, because all in all, they are manufactured by the same company. C172R has the Silver Crown stack that was installed in the factory, the Cherokee has the old generation units with gas discharge displays, plus completely different autopilot and auxiliary avionics.
http://a2asimulations.com/forum/viewtopic.php?f=107&t=35579
vs
http://a2asimulations.com/forum/viewtopic.php?f=115&t=40159
Anything older than that, and we're talking about analog instruments, that would take a lot of space and make Cherokee a much worse IFR platform. Besides, that's the equipment that was installed in a real airplane which was the main source of interior reference.
Actually, the autopilot has been completely rewritten so you could say it's a different unit now B) It now simulates all three servos (aileron, elevator, elevator trim), so you would be able to see how it really flies the plane, no cheating like the default FSX autopilot does. It also behaves like a real rate based autopilot, as opposed to the attitude based autopilots found in most other airplanes in FSX except Cherokee. A rate based autopilot uses the signal from the turn indicator and VSI, not from the attitude indicator, which makes it behave differently in some situations. During turns it maintains constant turn rate, not constant bank, and if you apply rudder when flying leveled, it will bank the aircraft to maintain zero turn rate, instead of turning the plane to maintain wings leveled.
We've also added optional HSI with simulated both Slave and Free modes. Installing HSI also changes the way how the autopilot operates.
There are more 3rd party GPS options available. Those GTN units from Flight1 work very nice and really transform it into glass cockpit.
Oh, and the clock has a fully adjustable backlight now. There are many improvements like that, it's not a copy&paste from the C172, otherwise it would be ready half a year ago ^_^